Typically, each engine carries its own oil tank which is generally cylindrically shaped with a feeding line mounted intermediate the vertical and horizontal center lines. The lowest point with respect to the horizon in the feeder line dictates the level of oil in the tank. In aircraft whose wings have different dihedral angles each tank mounted in the engine which is mounted such that it is vertical normal to the wing, will contain a different capacity.
This invention serves to eliminate this difference in oil capacity between tanks by designing each tank with a pair of interconnected cooperating compartments such that the upper one is an expansion receptical and is above the left wing dihedral and the lower tank is the oil reservoir and is below the right wing dihedral, or vice versa.